[Implant-associated fracture of the tibial plateau in cementless medial unicondylar knee prosthesis : Locking plate osteosynthesis].

THE PROBLEM: Cementless medial unicondylar knee prostheses with mobile inlays have proved to be successful and are increasingly being used worldwide; however, there is a risk of fracture of the medial tibial plateau in the postoperative healing phase.

THE SOLUTION: In most cases we observed split fractures starting from the keel of the implant. These can be treated with a small posteromedial locking plate, whereby the upper screws are inserted through the keel slot and then interlocked. This achieves an optimally strong bond between the implant and the screws and a stable construct.

SURGICAL TECHNIQUE: A longitudinal skin incision is made at the level of the keel slot. A radial T‑plate is placed subcutaneously. The plate is fixed with a lag screw in the middle section. The compression usually closes the fracture gap. Then three locking cortical bone screws are inserted through the keel slot in the transverse section of the plate. Distal fixation by locking or standard screws.

POSTOPERATIVE MANAGEMENT: Immediate pain-adapted partial weight bearing, unrestricted mobility. Healing of the fracture and full weight bearing mostly achieved after 4 weeks.